No, you can. The rule is that you can't turn 19 the June 15th BEFORE the start of your senior year. See CIF By-law 203 here: http://cifstate.org/images/PDF/State_Constitution_and_Bylaws/200_Series.pdf

In essence, the age restriction is such that you can't turn 20 anytime during your senior year and be eligible for high school sports. Note also that even this requirement can be waived under certain circumstances.